[git commit master] dd: fix conv=noerror w/o sync to not write out zeroed blocks

[Denys Vlasenko]

commit: http://git.busybox.net/busybox/commit/?id=f00cfdfae53d8ef623238ecb1001969b5f649cbd
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
dd_main                                             1480    1463     -17

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 coreutils/dd.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/coreutils/dd.c b/coreutils/dd.c
index 3fdfc23..627e7e7 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -286,25 +286,26 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
 	}
 
 	while (!(flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
-		if (flags & FLAG_NOERROR) /* Pre-zero the buffer if conv=noerror */
-			memset(ibuf, 0, ibs);
 		n = safe_read(ifd, ibuf, ibs);
 		if (n == 0)
 			break;
 		if (n < 0) {
+			/* "Bad block" */
 			if (!(flags & FLAG_NOERROR))
 				goto die_infile;
-			n = ibs;
 			bb_simple_perror_msg(infile);
-			/* GNU dd with conv=noerror skips over "bad blocks" */
+			/* GNU dd with conv=noerror skips over bad blocks */
 			xlseek(ifd, ibs, SEEK_CUR);
+			/* conv=noerror,sync writes NULs,
+			 * conv=noerror just ignores input bad blocks */
+			n = 0;
 		}
 		if ((size_t)n == ibs)
 			G.in_full++;
 		else {
 			G.in_part++;
 			if (flags & FLAG_SYNC) {
-				memset(ibuf + n, '\0', ibs - n);
+				memset(ibuf + n, 0, ibs - n);
 				n = ibs;
 			}
 		}
-- 
1.6.3.3